Space heating method and apparatus



June 4, 1963 T. 1 SHEPHERD 3,092,166

SPACE HEATING METHOD AND APPARATUS Filed Dec. 15, 1959 33 l l 5o IN VENTOR. T/mmas L. Symp/6rd AGENT United States Patent Ofce 3,092,166Patented June 4, 1963 3,092,166 SPACE HEAHNG METHGD AND APPARATUS ThomasL. Shepherd, Essex Fells, NJ., assigner to Air Reduction Company,Incorporated, New York, NX., a corporation of New Yori;

Filed Dec. 15, 1959, Ser. No. 359,624 6 Claims. (rl. 15S-11) Thisinvention relates to space heating and to burner constructions for spaceheating.

It is an object of the invention to provide an improved method of spaceheating by means of liquid fuel used in combination with flames of anoxy-fuel gas mixture. The Oxy-fuel gas mixture supplies a part of theheat, bu-t it serves two other important functions; it atomizes thestream of liquid fuel supplied to the combustion space, and it alsoprovides anchoring flames for preventing instability of the liquid fuelllame when the fuel supply is varied over a wide range to control therate of heating of the space.

The oxygen mixed with the fuel gas may be commercially pure oxygen or itmay be oxygen-enriched air, and for lower e'iciency operation, theoxygen may be that contained in air. The expression Oxy-fuel gasmixture, as used herein, means fuel gas mixed with air or commerciallypure oxygen, or combinations thereof, but in the preferred operation ofthe invention the mixture is one of fuel gas with commercially pureoxygen.

The expression atomize is used in the description in a broad sense toindicate a breaking up of the liquid stream for better and more completecombustion within the projected stream but without denoting anyparticular Vineness of particle size.

lt is another object of the invention to provide an improved burner foruse with liquid fuel, such as oil, together with fuel gas with whichoxygen is mixed in a combustion chamber of the burner. The burner is ofthe rocket type with a combustion chamber open at its discharge end, andorices through which the liquid and gaseous fuel, and the oxygen, aredischarged into the combustion chamber of the burner.

The combustion may take place entirely within the combustion chamber atlow rates of fuel delivery, but for higher rates of heating the flamingmixture of fuel and oxygen extends beyond the end of the burner and mayextend for great distances.

There is always some flame within 4the combustion space of the burner,however, and this ame provides stability for the burner over aremarkably wide range of fuel supply. Relatively low-velocity oxy-fuelgas flames within `the combustion chamber anchor the liquid fuel flame,and lower velocity Oxy-fuel flames near the base of the relativelyhigh-velocity flames serve to anchor these higher-velocity llames.

The heat output of burners made in accordance with this invention 'canbe varied from about 20,000 B.t.u. per hour to approximately 100,000,000B111. per hour by simply adjusting valves and without changing of anyburner parts. The arne length can be varied from about three to fortyfeet by simple valve adjustment. These values are given merely by way ofillustration for a burner of relatively small size. Other ranges can beobtained with burners of other sizes.

The invention also provides for control of the temperature and theoxidizing potential of the flame. Valve adjustments may be used tocontrol the oxygen-fuel ratio over a wide range, thereby exteringcontrol over flame temperature and the amount of excess oxygen whereexcess oxygen is desirable. Another advantage of the invention is thatit has rapid light-olf under cool conditions. High burner output can bedeveloped within a few seconds after light-off even though the burner isoperating into a cool space or in the open air.

Another advantage is compactness, which facilitates portable use andsimplifies applications in which size limitations exist. Theconstruction of the burner of this invention is one which can be usedfor burners of different size without changing the principle ofoperation which provides the inherent stability over such a wide rangeof operating conditions.

Other objects, features and advantages of the invention will appear orbe pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like referencecharacters indicate corresponding parts in all the views:

FEGURE l is a sectional view through a rocket-type burner made inaccordance with this invention;

FIGURE `2 is a sectional View taken on the line 2-2 of FIGURE 1;

FIGURE 3 is a fragmentary, diagrammatic, sectional View illustrating theoperation of the burner shown in FIGURES l and 2;

FEGURE 4 is a diagrammatic view showing the connection of the burnerwith sources of oxygen and fuel, and showing the burner located inposition to heat the interior of a furnace; and

FIGURE 5 is a diagrammatic end View showing the preferred slope at whichthe burner is located when used in a position confronting a similarburner at the other end of a furnace or other space to be heated.

FIGURE 1 shows a burner comprising a housing 10 having an end wall i12attached to the side wall of the housing by screw threads 14 and sealedagainst leakage by an O-ring 16.

Within the housing 10 there is a bundle of tubes. This bundle includeslong tubes 18 and short tubes 19, all of which extend through a circularpartition plate 20. 'I'he tubes 18 and 19 are rmly secured to thepartition plate 20,

The long tubes 18 also extend through a rearward partition plate 22 andare rmly secured thereto. The short tubes 19, however, terminate in thespace between the partition plates 20 and 22. The bundle of tubes isinserted into the housing 10, before the end Wall 12 is screwed into thehousing; and the rearward partition plate 22 contacts with a shoulder inthe housing 10, to determine the position of the bundle of tubes and tohold the bundle with the forward partition plate 20 substantially evenwith the forward end of the housing 10.

When the end wall 12 is screwed into position, there are chambers forgas on both sides of the rearward partition plate 22; and there is anO-n'ng 26 for preventing gas in either chamber from mixing with gas inthe other chamber. A baffle 28 on the end wall 12 extends across thechamber behind the rearward partition plate 22. There are holes in thisbathe for -admitting gas to the open ends of the long tubes 18.

The housing 10 has two threaded inlet openings 30 through which oxygenis supplied to the chamber behind the rearward partition plate 22. Thereis another threaded opening 32 through the wall of the housing 10 foradmitting fuel gas into the chamber ahead of the rearward partitionplate 22. Tube or pipe fittings are screwed into these openings 30 and32 and communicate with sources of oxygen and fuel gas.

From the construction thus far described, it will bc apparent thatoxygen will be discharged from the long tubes 18, and fuel gas from theshort tubes 19, into a chamber 36 in front of the forward partitionplate 20. This chamber 36 is enclosed within a double-wall sleeve 3Shaving an inner wall 40 spaced from an outer wall 42 along most of thelength of the sleeve 38. Water is 3 circulated through the space betweenthe inner wall 4i) and the outer wall 42. Y

There are iittings 46 connected with the sleeve 38 near V.its forwardend and communicating with the space be- ,discharge of cooling water.

' The walls 46 and 42 are preferably made or" copper for good heatconduction and they are separately threaded to the housing 18 withsealing rings 5U for preventing leakage along the threads. At theirforward ends, the walls 49 and 42 are connected by a litting 52 which isfree to move with respect to the outer wall 42 so as to compensate fordifferential expansion of the walls 4i! and 42. Sealing rings 50 preventleakage of water hetween the fitting 52 and the outer wall 42.

In ythe construction illustrated, there is `a single tube 56`forsupplying liquid fuel to the chamber 36. This tube 56 passes through theend wall 12 and through the partition plates 2t) and 22. In thepreferred construction .it is secured to the partition plates 2i) and 22and thus Y constitutes apart of the bundle of tubes. Where it passesthrough an opening in the end wall `12 a sealing ring 58 is provided forpreventing leakage of gas.

FIGURE 2 shows an end view of the forward partition plate 20. The tubes18 and 19 are angularly spaced around circles. The outer tubes 18 are at30 spacing from one another in the construction illustra-ted. There arethus twelve tubes located around the circle.l

The short tubes 19 are angularly spaced around a circle of intermediateydiameter and are 4spacedfrom one another 'by an angle of 45. Thisprovides for twelve of the short tubes 19. The inner long ltubes 18 'arelocated around a circle of small diameter with the angular spacing ofthe tubes 60. This provides for six of the inner tubes 18.V

Other combinations of tube spacing and numbers of tubes can be'lused butit is an important Ifeature of the A invention that the oxygen and fuel.gas issue ,from a plurality of tubes which are 'spaced from 'oneanother so that there is some clearance between the jets tof gas whichare discharged from the tubes. Yet the tubes must be close enoughtogether so that there is some mixing of fthe eddy currents from thedifferent gas streams. p

The importance of this tube spacing, and of the use of `a plurality oftubes, Vis brought out inV FIGURE 3. Oxygen from the bottom tube 18 isdischarged in a stream 62 and there lare some eddy currents 63 -Wheretheoxygen stream first issues from the tube 18. Fuel `gas issues from Ythe tube 19 in fa stream 65 which has eddy currents 66 at VVfrom thetubes-18 and 1,9, causes the Veddy currents 63 and 66 to Vbe extendedsomewhat further out from the tubes 18 and 19, Vbut the mixed gases ofthe edd-y currents are always at low velocity and provide stability forthe higher velocity flames within the combustion chamber 36.

It will be apparent that similar 'anchor flames will be producedibymixed gases of eddy currents at all of the clearances between full gasstreams and oxygenrstreams across the face of the forward partitionplate 2. Y

The oxygen and fuel gas streams 62 'and 65, respectively, spread as theyleave the tubes 18 and 19, and the main portions thereof come togethersome distance in front of the parti-tion plate 20. The streams 62 and 65are turbulent lstreams ias they are `discharged from the tubes 18 and19, and when they come together in the combustion chamber 36, they mixwith further turbulence. ln FGURE 3 the mixed gases are indicated by thesmall arcuate marks. The stream of liquid discharged from the vtube 56is indicated by shout dash lines and is marked with the referencecharacter 67. nere the stream 67 is broken up arnd mixed with the oxygenand fuel gas, this condition is indicated bythe small cross marks anddots in the mixing or combustion chamber 36. This showing isdiagrammatic and `simplified for clearer illustration.

The high temperature resulting from the burning of the mixed gas and theatomized liquid in the combustion chamber 36 produces further turbulencein the combustion chamber and provides additional energy `for vatomizingand partially vaporizing the liquid fuel from the stream 67.

One of the reasons that the present torch can develop such large heatoutput while small in size is that the wall of the combustion chamber iswater-cooled. This does deprive the torch of heat radiation from thesurfaces of the combustion chamber, such as i's present with other4types of rocket burners; but it does not decrease the stability of theburner of this invention Ibecause the stability of the ames is notdependent upon the radiation of heat from the inside sur-.faces of thecombustion chamber. The mixed gas flame provides an anchoring ame systemfor the atomized liquid combustion and the low velocity flames, producedby mixing of eddy currents from the separate gas streams, provideanchoring flames for theV Y mixed gas flame system.

No diliiculty is encountered in lighting the burner of this invention,even though ignition is performed in the open .air and with nostabilization contributed by heated refractory material of a surroundingenclosure. The technique used is to turn on the supply of fuel gas aloneand the llame length can be increased by simply increasing theV rate ofVliquid fuel feed and concurrently increasing the -oxygen flow tomaintain a stable and relatively quiet combustion.

YA wide variation in the length of the llame can be obtained byadjusting the ratio of fuel gas to liquid fuel. For example, when theamount of fuel gas is reduced, there is a larger amount of oxygen mixedwith the atomized liquid fuelV close to the Vregion of originalatomizing of the liquid fuel, and this tends to produce a short llame.On the other hand, when the amount of fuel gas is in. creased, theoxygen-fuel gas flame which atomizes the liquid stream containssubstantial quantities of products of combustion of the fuel gas aud-amuch lower percentage Vof oxygen. This has the effect of preventingignition of the liquid fuel until it has traveled a considerabledistance from the discharge tube 56 and it produces a very long, flamethrower type of ame.

Experience indicates that in order to have the anchoring ames producedby the eddy currents, the spacing of the tubes which supply the oxygenand the fuel gas should not be greater than twice the `diameter of thetubes, when the tubes are of the same diameter. Ifthe oxygen and thefuel gas tubes are of different diameters, then the relations should besuch that the spacing is not greater than twice the diameter of the tubewhich has the larger diameter. Since it is necessary to have someclearance in which the eddy current gases can mix and burn, the oxygenand fuel gas tubes should not be too close together. It appears that thespacing should not be less than one half of the diameter of the tubes,when they are both the same diameter; and not less than one half thediameter of the smaller tube when there is a difference in the tubediameters. This range is approximate and is for a burner in which thecombustion chamber 36 is long enough to obtain a mixing of the majorportions of the gas streams before their discharge from the combustionchamber.

The ratio of the combustion chamber length to its inside diameterdepends upon the service for which the burner is intended. It may bebetween 1 to l and approximately 12 to l. In the preferred construction,the combustion chamber has an inside diameter of approximately 21/2inches and a length of between 12 and 24 inches. These Values are givenmerely by way yof illustration.

The oxygen and fuel gas streams discharged from the tubes at thepartition plate 20 issue at substantial velocity :and they impart somekinetic energy to the particles of liquid fuel when they atomize thestream of liquid fuel. The initial velocity of the liquid fuel stream,as it issues from the discharge end of its supply tube, must beSullicient, after making allowances for the kinetic energy which the gasstreams will supply, to carry the liquid stream along a trajectory thatwill clear the side wall of the combustion chamber. A lower velocity ofliquid stream is objectionable because any liquid Iwhich strikes theside wall of the combustion chamber is cooled by contact with thecombustion chamber and dribbles out of the end of the chamber withoutbeing taken up lby the flame system.

If adjustments are made which approach instability, the llame systemwill produce a screaming noise. Por example, if the burner is operatedwith the fuel supply at a very low pressure, the screamingcharacteristic of instability is produced, but the burner will operateover considerable screaming range, and with the sound spread over a Wideregion of wave lengths, without actually losing the ame.

FIGURE 4 shows a burner, made in accordance with this invention, andhaving its housing supported from an end wall 72 of a furnace 75 Oxygenis supplied to the burner through piping 78 which includes a pressureregulator 79. Fuel gas is supplied through piping 81 including apressure regulator 82. Liquid fuel is supplied through piping 84 and aliquid pump 86 is driven by a motor 88.

The rate of ilow of the oxygen and fuel gas is controlled by adjustingthe output pressure of the regulators 79 and 82. The rate of flow of theliquid fuel is controlled by adjusting the speed of the motor 88 througha speed con- .trol 90. A llame 92 discharged from the end of the burnermay be increased in size until it substantially lls the entire length ofthe furnace 75.

In FIGURE 4 there is a second burner 95 at the opposite end of thefurnace from the yburner 7l. These burners are used alternately, andwhen one burner is in operation, it is likely to blow molten metal or`slag toward the other burner. If a large mass of such material entersthe combustion chamber of the inoperative burner, it may stick to thepartition plate and plug the openings through which the oxygen fuel gasand liquid fuel are discharged when the burner is in operation.

This result is avoided by having the burners 71 and 95 constructed withlong combustion chambers and by tilting the burners downwardly so thatparticles projected lengthwise of the furnace, as indicated by thearrows 97 in FIGURE 4, will not strike directly against the partitionplate within the burner.

This result is illustrated in FIGURE 5 -where the top edge 99 of thefront end of the combustion chamber of the burner 95 is at a levelslightly lower than a bottom edge 101 of the partition plate. Theparticles are considered as being projected horizontally and in order toprevent them from striking the partition plate 20, the

6 torch must be at an angle of A to the horizontal. It will be apparentfrom FIGURE 5 that the angle A is equal to arc tan Where d is the insidediameter of the combustion chamber of the torch 95 and L is the lengthof the combust-ion chamber of the burner.

The preferred rembodiment of this invention has been illustrated anddescribed, but changes and modifications can be made and some featurescan be used in different combinations without departing from theinvention as defined in lthe claims.

What is claimed is:

1. The method of heating a space by burner means including a burnerlocated near one end of the space, which method comprises projecting aturbulent Oxy-fuel gas stream from the burner and burning the Oxy-fuelstream at least partially within the burner, forming anchoring flames bydelivering the oxygen gas and fuel gas for said Oxy-fuel gas flame in aplurality of substantially parallel, closely adjacent streams thatcreate between them a relatively lower velocity mixture of said fuel gasand oxygen gas drawn from said streams and which burns in a ame zone inadvance of the Oxy-fuel gas flame of said turbulent gas stream,projecting a stream of liquid fuel from the burner into Iche ame of saidturbulent gas stream, atornizing the stream of liquid fuel by contactwith said turbulent gas stream and thereby admixing finely dispersedparticles of liquid fuel with the turbulent gas stream, burning theliquid fuel while mixed with the llame and with products of combustiontherefrom to form a ame system, adjusting the supply of liquid fuel toregulate the heating of said space, continuing steady combustion of theflame of burning liquid fuel by contact of the burning liquid `fuel withthe Oxy-fuel gas flame of said turbulent gas stream, and continuingsteady combustion of the VOxy-fuel gas llame of said turbulent gasstream by contact of the turbulent gas stream with said anchorring damesalong the Oxy-fuel gas llame at a location before the Oxy-fuel gas llamemixes in combustible proportions With the stream of liquid fuel,increasing the volurne and velocity of the liquid fuel supply toincrease the length of the llame system, and discharging the products ofcombustion of the ame system into the space to be heated.

2. The method of heating described in claim l characterized by burningonly a portion of the liquid fuel and the Oxy-fuel gas stream within theburner before discharging the ame system into the space to be heated,and controlling the heating of the space by regulating the ylength ofthe llame system.

3. The method of heating described in claim il, characterized bylocating the burner substantially at one end of an elongated space ofsubstantial length, controlling the hea-ting by Varying the length ofthe flame system, and increasing the ilame system to substantially thefull length of the space for maximum heating.

4. 'Ihe method of heating a space by means of a burner having anelongated combustion chamber with a discharge opening through which aspace heating flame is discharged into said space, which methodcomprises delivering a plurality of separate, substantially parallelstreams of oxygen gas and fuel gas substantially axially into theelongated combustion chamber, turbulently mixing said gas streams into acombustible mixture at a intermediate zone of said chamber, ignitingsaid mixture to form a main flame at least partially within saidcombustion chamber, discharging the `oxygen and fuel gas streams intothe chamber closely adjacent to one another and with the space betweenadjacent streams constituting zones into which a portion of the gas fromeach fof the respective streams is drawn -to form a relatively lowvelocity combustible gas mixture in said zones, burning said relativelylow velocity gas mixture close to the root 'of the main flame to fermanchoring flames for said main flame, discharging .a stream of liquidfuel into said intermediate zone toward said discharge outlet toeffectively mix said fuel stream in said main flame, and burning saidliquid fuel at least partly in said chamber and directing the ameproduced thereby and said main flame into said space to be heated.

5. The method described in claim 4 characterized by regulating therelative flows of said oxygen gas streams andfuel gas streams to controlthe `oxygen for combus tion of the liquid fuel.

6. A combination liquid `and gaseous fuel burner comprising anelongated, unobstructed combustion chamber having an open discharge endand an opposite closed end through which a plurality -of substantiallyparallel gas passageways extend to said chamber, adjacent alternate onesof said passageways being connected respectively to sources of an oxygengas and a fuel gas to deliver corresponding, spaced,substantially-parallel streams of an oxygen gas and a fuel gas into theclosed `end of said chamber directed substantially toward said chamberdischarge opening, said gas streams merging With onewanother at anintermediate zone of said chamber, in a relatively high velocitycombustion mixture of said oxygen gas and fuel gas and burning in aflame con-lined at least in part Vby the walls of said chamber, theparallel gas passageways being closely adjacent to one another with zonbetween them into which gas from the streams is drawn to form larelatively low velocity mixture of oxygen gas and fuel gas whosecombusti-on forms anchoringV ames contiguous with said gas streamseectively pre- Y venting extinction of the flame formed by combustion ofsaid relatively high velocity combustion mixture, and a liquid deliverypassageway extending substantially centrally through said closedrend ofsaid chamber having means for discharging Ia vstream of liquid fueltherethrough toward said chamber discharge opening into said relativelyhigh velocity gas mixture wherein said relatively high velocity mixtureeffectively atomizes said ,liquid stream to facilitate combustionthereof, and gas ow regulating means for the oxygen vand fuel gas, theregulating means for the oxygen and fuel gas being independentlyadjustable for controlling the supply of oxygen gas for combustion Withsaid liquid fuel by `controlling the relative flows of said oxygen gasand fuel gas streams.

References Cited in the file of this patent UNITED STATES PATENTS664,526 Blass Dec. 25, 1900 1,416,990 Smith May 23, 1922 1,476,913Nordensson etal Dec. 11, 1923 1,729,677 Miller Oct. 1, 1929 2,084,830Barnard et al June 22, 19137 2,333,531 Ferguson Nov. 2, 1943 2,480,459Fletcher Aug. 30, 1949 2,625,466 Williams Ian. 13, 1953 2,706,887 GrowApr. 26, 1955 2,911,035 Nieman et al. Nov. 3, 1959 2,931,430 MarshallApr. 5, 1960 FOREIGN PATENTS 819,977 Great Britain Sept. 9, 1959 820,820Great Britain Sept. 30, 1959

6. A COMBINATION LIQUID AND GASEOUS FUEL BURNER COMPRISING AN ELONGATED,UNOBSTRUCTED COMBUSTION CHAMBER HAVING AN OPEN DISCHARGE END AND ANOPPOSITE CLOSED END THROUGH WHICH A PLURALITY OF SUBSTANTIALLY PARALLELGAS PASSAGEWAYS EXTEND TO SAID CHAMBER, ADJACENT ALTERNATE ONES OF SAIDPASSAGEWAYS BEING CONNECTED RESPECTIVELY TO SOURCES OF AN OXYGEN GAS ANDA FUEL GAS TO DELIVER CORRESPONDING, SPACED, SUBSTANTIALLY-PARALLELSTREAMS OF AN OXYGEN GAS AND A FUEL GAS INTO THE CLOSED END OF SAIDCHAMBER DIRECTED SUBSTANTIALLY TOWARD SAID CHAMBER DISCHARGE OPENING,SAID GAS STREAMS MERGING WITH ONE ANOTHER AT AN INTERMEDIATE ZONE OFSAID CHAMBER, IN A RELATIVELY HIGH VELOCITY COMBUSTION MIXTURE OF SAIDOXYGEN GAS AND FUEL GAS AND BURNING IN A FLAME CONFINED AT LEAST IN PARTBY THE WALLS OF SAID CHAMBER, THE PARALLEL GAS PASSAGEWAYS BEING CLOSELYADJACENT TO ONE ANOTHER WITH ZONES BETWEEN THEM INTO WHICH GAS FROM THESTREAMS IS DRAWN TO FORM A RELATIVELY LOW VELOCITY MIXTURE OF OXYGEN GASAND FUEL GAS WHOSE COMBUSTION FORMS ANCHORING FLAMES CONTIGUOUS WITHSAID GAS STREAMS EFFECTIVELY PREVENTING EXTINCTION OF THE FLAME FORMEDBY COMBUSTION OF SAID RELATIVELY HIGH VELOCITY COMBUSTION MIXTURE, AND ALIQUID DELIVERY PASSAGEWAY EXTENDING SUBSTANTIALLY CENTRALLY THROUGHSAID CLOSED END OF SAID CHAMBER HAVING MEANS FOR DISCHARGING A STREAM OFLIQUID FUEL THERETHROUGH TOWARD SAID CHAMBER DISCHARGE OPENING INTO SAIDRELATIVELY HIGH VELOCITY GAS MIXTURE WHEREIN SAID RELATIVELY HIGHVELOCITY MIXTURE EFFECTIVELY ATOMIZES SAID LIQUID STREAM TO FACILITATECOMBUSTION THEREOF, AND GAS FLOW REGULATING MEANS FOR THE OXYGEN ANDFUEL GAS, THE REGULATING MEANS FOR THE OXYGEN AND FUEL GAS BEINGINDEPENDENTLY ADJUSTABLE FOR CONTROLLING THE SUPPLYING OF OXYGEN GAS FORCOMBUSTION WITH SAID LIQUID FUEL BY CONTROLLING THE RELATIVE FLOWS OFSAID OXYGEN GAS AND FUEL GAS STREAMS.